"ddmmyyyy;hh:mm:ss;XX"

You could compress your data a little bit.

For instance, one byte for "dd" ( 1 to 31 )
one byte for mm (1 to 12)
one byte for yy, and one for the other half of yy
etc. etc.

That would decrease your requirements by half. So maybe you could use a large Pic chip. But if you need to go to external, it is probably not worth it, as you will have ample space.